Variable displacement axial piston pumps and motors in which a swashplate is tilted relative to a housing for controlling the displacement of pistons within piston bores of a rotating barrel are well known. Many of such pumps and motors include a lever secured to the swashplate and has a distal end positioned adjacent an actuator mounted on or within the pump housing. Heretofore, the distal end of the lever has been connected to the actuator through a pin extending laterally outwardly for engagement with a slider that interfaces with the actuator so that linear movement of the actuator causes tilting movement of the swashplate.
One of the problems encountered with such arrangements is that transmitting the forces from the actuator to the lever through a pin cantilevered from the lever imparts a twisting force on the lever in addition to the normal actuating forces needed to tilt the swashplate. This complex loading on the lever results in the need for a more robust lever to minimize deflections in the lever. Deflections in the lever can create slight variations in the tilted position of the swashplate relative to the movement of the actuator.
Moreover, the contact area between the cylindrical surface of the pin and the slider is relatively small causing high contact stresses at the mating surfaces which can lead to premature failure due to galling or pitting of the mating surfaces. Finally, the pin type of connection increases the difficulty of assembling the barrel, pistons, swashplate and so forth within the housing of the pump or motor.
Thus, it would be desirable to provide a swashplate actuating mechanism for a variable displacement axial piston pump or motor in which the actuating forces transmitted from the actuator to the lever are in a straight line relationship to minimize torsional loading on the actuator lever. It would also be desirable to provide such actuating mechanism with larger contact surfaces between the mating components to reduce high contact stresses therebetween.
The present invention is directed to overcoming one or more of the problems as set forth above.